1. Field of the Invention
Exemplary embodiments of the present invention relate to an apparatus and a method for determining an overlap distance of an optical head. More particularly, exemplary embodiments of the present invention relate to a digital exposure device and a method for determining an overlap distance of an optical head used for a digital exposure.
2. Description of the Related Art
Generally, in order to form a metal pattern of a thin-film transistor (“TFT”) by using a metal layer and a photoresist layer which may be sequentially formed in a substrate, the metal pattern may be formed using a mask having a design of a metal pattern which may be disposed on the photoresist layer. For example, the photoresist layer can be exposed and developed by providing light to an upper portion of the mask to form a photoresist pattern in which the design of the mask may be reflected. The metal layer can be etched by using the photoresist pattern serving as an etch stop layer so that the metal pattern may be formed. However, when a display substrate includes a plurality of metal patterns, a plurality of masks by the number of the metal patterns may be required due to different patterns. Moreover, when the designs of the metal patterns are changed, the design of the mask may also be required to be changed so that a mask may be re-produced. Since a reproduction cost of the mask is relatively high, reproducing the mask may increase the manufacturing cost of a display substrate.
In order to overcome the problem, an approach has been introduced to an exposure device capable of providing a substrate with beams without using a mask. In the exposure device, the beams may be activated or inactivated to selectively be provided to the substrate so that photoresist patterns dependent on a shape can be defined by the activation or inactivation of the beams. Since an area covered by light provided from the exposure device is limited, the exposure device or the substrate is moved to scan in several times when a photoresist pattern is formed on a large-sized substrate by using the exposure device. In this way, the substrate may fully be exposed by the exposure device.
However, when the substrate is scanned by the exposure device, an overlapped area may be generated. In this approach, the overlapped area of the substrate can be exposed by the exposure device at least more than two times so that unnecessary exposures in terms of generating patterns can not only be a burden to manufacturing a display substrate but adversely affect a manufacturing yield since a uniformity of the photoresist pattern may be decreased.